Commercial riding mowers of the type used on golf courses are relatively large machines which utilize cutting reels as opposed to rotary blades. Two or three such cutting reels are typically provided across the front of the mower, with one or more cutting reels being positioned in trailing relationship behind the gaps between the cutting reels in the front. In order for the cutting reels to be effective, they must of course be in direct contact with the grass at all times, following the contour and undulations of the terrain as the mower is driven along. The Toro Company, which is the assignee hereof, manufactures and sells several examples of such mowers.
It will be appreciated that the speed of such mowers, and thus the time necessary to cut a particular tee or fairway on a golf course, for example, depends upon the ability of their cutting units to follow the terrain. This in turn depends upon the roughness of the terrain, type of grass and its degree of wetness, cutting height, etc. Cutting the grass on a golf course is a recurring, and time consuming task. While the grass is being cut, that particular tee or fairway is taken out of service and so it is desirable to drive the mower as fast as possible while maintaining the desired cutting height.
In the past, the cutting reels were relatively heavy and thus tended to follow the contours of the ground satisfactorily up to a certain speed. Additional weight was sometimes added to help them follow the ground contours, however, this made the cutting reels difficult to repair and replace. It also increased the overall weight of the mower, thus decreasing .[.manueverability.]. .Iadd.maneuverability .Iaddend.and causing undue compaction of the soil.
More recently, lightweight cutting reels, which can be easily removed for replacement and repair as necessary, have become available. In addition, such .[.ligh.]. .Iadd.light .Iaddend.weight cutting reels have helped to reduce overall weight of the mower and undue soil compaction, while improving maneuverability. On the other hand, such lightweight cutting reels have some drawbacks in terms of quality of cut and maintaining the desired cutting height because they tend to ride above the ground surface cushioned by a layer of grass. Merely adding extra weight is at cross purposes to the advantages of lightweight cutting reels.
Various counterweight and counterbalance arrangements have been utilized for this purpose in the past. For example, U.S. Pat. Nos. 1,210.879, 1,293,287 and 1,330,293 to Worthington and 1,446,265 to Murphy are representative of the prior art in this regard. Such arrangements have tended to be overly complicated and expensive.
A need has thus arisen for an improved arrangement for downloading lightweight cutting reels by means of adjustable spring assemblies in order to effect optimal cutting.